(a) Technical Field
The present invention relates to a bumper beam for a vehicle. More particularly, it relates to a plastic composite bumper beam for a vehicle, which can achieve a reduction in weight and cost reduction while at the same time having excellent mechanical properties and crash performance.
(b) Background Art
In general, a bumper assembly for a vehicle is mounted on the front and rear ends of a vehicle body, respectively, to absorb impact in the event of a collision, thus protecting a driver and passengers during an accident and preventing deformation of the vehicle body. A basic configuration of the vehicle bumper assembly is shown in FIG. 1. As shown in the figure, the vehicle bumper assembly generally includes a bumper cover 10 for covering or enclosing an entire bottom area of the front or rear end of the vehicle body, an energy absorber 20 for absorbing vibrations and impact energy translated of the bumper cover 10, a bumper beam (or a back beam) 30 located at the rear of the energy absorber 20 to protect the vehicle body from damage upon impact, and a stay 40 for fixing and supporting the bumper beam 30 to the vehicle body.
In a compact vehicle, the bumper assembly may be composed of only the bumper cover, the bumper beam, and the stay, without the energy absorber to reduce the weight. In this configuration, the bumper beam is configured to efficiently absorb the impact energy. The bumper beam may be formed from various materials such as steel, aluminum, plastic composite, etc., according to the vehicle model or required performance.
U.S. Pat. No. 5,290,079 and U.S. Pat. No. 6,286,879 each disclose a fiber-reinforced plastic composite bumper beam, and U.S. Pat. No. 6,817,638 discloses a bumper beam formed of a glass mat-reinforced thermoplastic (GMT), having a C-shaped section, and including a reinforcing sheet. European Patent No. 0945253 discloses a bumper beam formed of a filled GMT composite material containing polyolefin and glass fibers, and Korean Patent Publication No. 10-2007-0111812 discloses a bumper beam having an external beam member formed of a GMT material and an internal beam member formed of a steel material.
Moreover, Korean Patent Application Publication No. 10-2010-0104457 discloses a bumper beam using a GMT or long fiber-reinforced composite, and Korean Patent Application Publication No. 10-2010-0006672 discloses a bumper beam including a unidirectional reinforcing fiber sheet introduced by an LFT-D process or integrally formed.
These conventional plastic composite bumper beams, as can be seen by the descriptions above, are mainly formed of GMT composites including unidirectional continuous fibers by press molding (i.e., compression molding) the materials into the shape of the bumper beam.
Typically, the GMP bumper beam is formed to have a thickness of about 4 to 15 mm to ensure the strength and crash performance. However, it is necessary to reduce the thickness of the bumper to enhance the degree of freedom in the design of the bumper and, at the same time, improve the absorption efficiency of impact energy to reduce the repair cost which are associated with an accident.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.